Electromotive series, also called the electrochemical series or activity series, is a listing of metals and hydrogen with respect to their tendency to lose electrons during chemical reactions. Metals that lose electrons more readily than hydrogen does are listed in the series before hydrogen. Those that lose electrons less readily than hydrogen follow hydrogen in the listing. The following is the order of some commonly used elements in the electromotive series: potassium, calcium, sodium, magnesium, aluminum, zinc, iron, nickel, tin, lead, hydrogen, copper, mercury, silver, platinum, gold.
Chemists use the electromotive series to predict how reactive a metal will be toward other materials. In general, the greater a metal’s tendency to lose electrons, the more reactive it will be. Thus, metals that appear before others in the series tend to be more reactive than those that follow them. For example, a chemist would expect iron to react with oxygen more readily than gold does, because iron is listed before gold in the electromotive series. Iron reacts with oxygen in air to form rust, but gold does not. Gold maintains its shiny appearance in the presence of oxygen and is not corroded by it.
